Concrete block mold with moveable liner

ABSTRACT

A mold assembly for molding concrete blocks including at least one mold cavity including a plurality of liner plates forming sides walls of the mold cavity, wherein at least one of the liner plates is moveable between an extended position and a retracted position relative to an interior of the mold cavity. The mold assembly further includes a linear actuator having an actuator axis, a first drive linkage coupled to the linear actuator, and a second drive linkage coupled to the first drive linkage and positioned off-axis of the actuator axis and in mechanical communication with the at least one moveable liner plate, wherein the linear actuator provides forces in opposite directions along the actuator axis to the first drive linkage to drive the second drive linkage toward and away from the interior of the mold cavity to direct movement of the at least one moveable liner plate between the extended and retracted positions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/591,624 (Publication No. 2007/0104819) filed on Nov. 1, 2006, whichis a divisional of U.S. Pat. No. 7,261,548 filed on Jun. 29, 2004, whichis a continuation-in-part of U.S. Pat. No. 7,156,645 filed Jul. 29,2003, each of which is incorporated by reference herein in its entirety.

THE FIELD OF THE INVENTION

The present invention relates to concrete block molds, and moreparticularly to a concrete block mold adapted for use with a concreteblock machine and having at least one moveable liner.

BACKGROUND OF THE INVENTION

Concrete blocks, also referred to as concrete masonry units (CMU's), aretypically manufactured by forming them into various shapes using aconcrete block machine employing a mold frame assembled so as to form amold box. A mold cavity having a negative of a desired shape of theblock to be formed is provided within the mold box. A support board, orpallet, is moved via a conveyor system onto a pallet table. The pallettable is moved upward until the pallet contacts and forms a bottom ofthe mold box. The cavity is then filled with concrete by a moveablefeedbox drawer.

As soon as the mold is filled with concrete, the feedbox drawer is movedback to a storage position and a plunger, or head shoe assembly,descends to form a top of the mold.

The head shoe assembly is typically matched to the top outside surfaceof the mold cavity and is hydraulically or mechanically pressed down onthe concrete. The head shoe assembly compresses the concrete to adesired pounds-per-square-inch (psi) rating and block dimension whilesimultaneously vibrating the mold along with the vibrating table,resulting in substantial compression and optimal distribution of theconcrete throughout the mold cavity.

Because of the compression, the concrete reaches a level of hardnessthat permits immediate stripping of the finished block from the mold. Toremove the finished block from the mold, the mold remains stationarywhile the shoe and pallet table, along with the corresponding pallet,are moved downward and force the block from the mold onto the pallet. Assoon as the bottom edge of the head shoe assembly clears the bottom edgeof the mold, the conveyor system moves the pallet with the finishedblock forward, and another pallet takes its place under the mold. Thepallet table then raises the next pallet to form a bottom of the moldbox for the next block, and the process is repeated.

For many types of CMU's (e.g., pavers, patio blocks, light weightblocks, cinder blocks, etc.), but for retaining wall blocks andarchitectural units in particular, it is desirable for at least onesurface of the block to have a desired texture, such as a stone-liketexture. One technique for creating a desired texture on the blocksurface is to provide a negative of a desired pattern or texture on theside walls of the mold. However, because of the way finished blocks arevertically ejected from the mold, any such pattern or texture would bestripped from the side walls unless they are moved away from the moldinterior prior to the block being ejected.

One technique employed for moving the sidewalls of a mold involves theuse of a cam mechanism to move the sidewalls of the mold inward and anopposing spring to push the sidewalls outward from the center of themold. However, this technique applies an “active” force to the sidewallonly when the sidewall is being moved inward and relies on the energystored in the spring to move the sidewall outward. The energy stored inthe spring may potentially be insufficient to retract the sidewall ifthe sidewall sticks to the concrete. Additionally, the cam mechanism canpotentially be difficult to utilize within the limited confines of aconcrete block machine.

A second technique involves using a piston to extend and retract thesidewall. However, a shaft of the piston shaft is coupled directly tothe moveable sidewall and moves in-line with the direction of movementof the moveable sidewall. Thus, during compression of the concrete bythe head shoe assembly, an enormous amount of pressure is exerteddirectly on the piston via the piston shaft. Consequently, a pistonhaving a high psi rating is required to hold the sidewall in placeduring compression and vibration of the concrete. Additionally, thedirect pressure on the piston shaft can potentially cause increased wearand shorten the expected life of the piston.

SUMMARY OF THE INVENTION

One embodiment provides a mold assembly for molding concrete blocksincluding at least one mold cavity including a plurality of liner platesforming sides walls of the mold cavity, wherein at least one of theliner plates is moveable between an extended position and a retractedposition relative to an interior of the mold cavity. The mold assemblyfurther includes a linear actuator having an actuator axis, a firstdrive linkage coupled to the linear actuator, and a second drive linkagecoupled to the first drive linkage and positioned off-axis of theactuator axis and in mechanical communication with the at least onemoveable liner plate, wherein the linear actuator provides forces inopposite directions along the actuator axis to the first drive linkageto drive the second drive linkage toward and away from the interior ofthe mold cavity to direct movement of the at least one moveable linerplate between the extended and retracted positions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one exemplary embodiment of a moldassembly having moveable liner plates according to the presentinvention.

FIG. 2 is a perspective view of one exemplary embodiment of a gear driveassembly and moveable liner plate according to the present invention.

FIG. 3A is a top view of gear drive assembly and moveable liner plate asillustrated in FIG. 2.

FIG. 3B is a side view of gear drive assembly and moveable liner plateas illustrated in FIG. 2.

FIG. 4A is a top view of the mold assembly of FIG. 1 having the linerplates retracted.

FIG. 4B is a top view of the mold assembly of FIG. 1 having the linerplates extended.

FIG. 5A illustrates a top view of one exemplary embodiment of a gearplate according to the present invention.

FIG. 5B illustrates an end view of the gear plate illustrated by FIG.5A.

FIG. 5C illustrates a bottom view of one exemplary embodiment of a gearhead according to the present invention.

FIG. 5D illustrates an end view of the gear head of FIG. 5C.

FIG. 6A is a top view of one exemplary embodiment of a gear trackaccording to the present invention.

FIG. 6B is a side view of the gear track of FIG. 6A.

FIG. 6C is an end view of the gear track of FIG. 6A.

FIG. 7 is a diagram illustrating the relationship between a gear trackand gear plate according to the present invention.

FIG. 8A is a top view illustrating the relationship between oneexemplary embodiment of a gear head, gear plate, and gear trackaccording to the present invention.

FIG. 8B is a side view of the illustration of FIG. 8A.

FIG. 8C is an end view of the illustration of FIG. 8A.

FIG. 9A is a top view illustrating one exemplary embodiment of a gearplate being in a retracted position within a gear track according to thepresent invention.

FIG. 9B is a top view illustrating one exemplary embodiment of a gearplate being in an extended position from a gear track according to thepresent invention.

FIG. 10A is a diagram illustrating one exemplary embodiment of driveunit according to the present invention.

FIG. 10B is a partial top view of the drive unit of the illustration ofFIG. 10A.

FIG. 11A is a top view illustrating one exemplary embodiment of a moldassembly according to the present invention.

FIG. 11B is a diagram illustrating one exemplary embodiment of a geardrive assembly according to the present invention.

FIG. 12 is a perspective view illustrating a portion of one exemplaryembodiment of a mold assembly according to the present invention.

FIG. 13 is a perspective view illustrating one exemplary embodiment of agear drive assembly according to the present invention.

FIG. 14 is a top view illustrating a portion of one exemplary embodimentof a mold assembly and gear drive assembly according to the presentinvention.

FIG. 15A is a top view illustrating a portion of one exemplaryembodiment of a gear drive assembly employing a stabilizer assembly.

FIG. 15B is a cross-sectional view of the gear drive assembly of FIG.15A.

FIG. 15C is a cross-sectional view of the gear drive assembly of FIG.15A.

FIG. 16 is a side view illustrating a portion of one exemplaryembodiment of a gear drive assembly and moveable liner plate accordingto the present invention.

FIG. 17 is a block diagram illustrating one exemplary embodiment of amold assembly employing a control system according to the presentinvention.

DETAILED DESCRIPTION

In the following Detailed Description, reference is made to theaccompanying drawings which form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. In this regard, directional terminology, such as “top,”“bottom,” “front,” “back,” “leading,” “trailing,” etc., is used withreference to the orientation of the Figure(s) being described. Becausecomponents of embodiments of the present invention can be positioned ina number of different orientations, the directional terminology is usedfor purposes of illustration and is in no way limiting. It is to beunderstood that other embodiments may be utilized and structural orlogical changes may be made without departing from the scope of thepresent invention. The following detailed description, therefore, is notto be taken in a limiting sense, and the scope of the present inventionis defined by the appended claims.

FIG. 1A is a perspective view of one exemplary embodiment of a moldassembly 30 having moveable liner plates 32 a, 32 b, 32 c and 32 daccording to the present invention. Mold assembly 30 includes a drivesystem assembly 31 having side-members 34 a and 34 b and cross-members36 a and 36 b, respectively having an inner wall 38 a, 38 b, 40 a, and40 b, and coupled to one another such that the inner surfaces form amold box 42. In the illustrated embodiment, cross members 36 a and 36 bare bolted to side members 34 a and 34 b with bolts 37.

Moveable liner plates 32 a, 32 b, 32 c, and 32 d, respectively have afront surface 44 a, 44 b, 44 c, and 44 d configured so as to form a moldcavity 46. In the illustrated embodiment, each liner plate has anassociated gear drive assembly located internally to an adjacent moldframe member. A portion of a gear drive assembly 50 corresponding toliner plate 32 a and located internally to cross-member 36 a is shownextending through side-member 34 a. Each gear drive assembly isselectively coupled to its associated liner plate and configured to movethe liner plate toward the interior of mold cavity 46 by applying afirst force in a first direction parallel to the associatedcross-member, and to move the liner plate away from the interior of moldcavity 46 by applying a second force in a direction opposite the firstdirection. Side members 34 a and 34 b and cross-members 36 a and 36 beach have a corresponding lubrication port that extends into the memberand provides lubrication to the corresponds gear elements. For example,lubrication ports 48 a and 48 b. The gear drive assembly and moveableliner plates according to the present invention are discussed in greaterdetail below.

In operation, mold assembly 30 is selectively coupled to a concreteblock machine. For ease of illustrative purposes, however, the concreteblock machine is not shown in FIG. 1. In one embodiment, mold assembly30 is mounted to the concrete block machine by bolting side members 34 aand 34 b of drive system assembly 31 to the concrete block machine. Inone embodiment, mold assembly 30 further includes a head shoe assembly52 having dimensions substantially equal to those of mold cavity 46.Head shoe assembly 52 is also configured to selectively couple to theconcrete block machine.

Liner plates 32 a through 32 d are first extended a desired distancetoward the interior of mold box 42 to form the desired mold cavity 46. Avibrating table on which a pallet 56 is positioned is then raised (asindicated by directional arrow 58) such that pallet 56 contacts andforms a bottom to mold cavity 46. In one embodiment, a core bar assembly(not shown) is positioned within mold cavity 46 to create voids withinthe finished block in accordance with design requirements of aparticular block.

Mold cavity 46 is then filled with concrete from a moveable feedboxdrawer. Head shoe assembly 52 is then lowered (as indicated bydirectional arrow 54) onto mold 46 and hydraulically or mechanicallypresses the concrete. Head shoe assembly 52 along with the vibratingtable then simultaneously vibrate mold assembly 30, resulting in a highcompression of the concrete within mold cavity 46. The high level ofcompression fills any voids within mold cavity 46 and causes theconcrete to quickly reach a level of hardness that permits immediateremoval of the finished block from mold cavity 46.

The finished block is removed by first retracting liner plates 32 athrough 32 d. Head shoe assembly 52 and the vibrating table, along withpallet 56, are then lowered (in a direction opposite to that indicatedby arrow 58), while mold assembly 30 remains stationary so that headshoe assembly 56 pushes the finished block out of mold cavity 46 ontopallet 52. When a lower edge of head shoe assembly 52 drops below alower edge of mold assembly 30, the conveyer system moves pallet 56carrying the finished block away and a new pallet takes its place. Theabove process is repeated to create additional blocks.

By retracting liner plates 32 a through 32 b prior to removing thefinished block from mold cavity 46 liner plates 32 a through 32 dexperience less wear and, thus, have an increased operating lifeexpectancy. Furthermore, moveable liner plates 32 a through 32 d alsoenables a concrete block to be molded in a vertical position relative topallet 56, in lieu of the standard horizontal position, such that headshoe assembly 52 contacts what will be a “face” of the finished concreteblock. A “face” is a surface of the block that will be potentially beexposed for viewing after installation in a wall or other structure.

FIG. 2 is a perspective view 70 illustrating a moveable liner plate andcorresponding gear drive assembly according to the present invention,such as moveable liner plate 32 a and corresponding gear drive assembly50. For illustrative purposes, side member 34 a and cross-member 36 arenot shown. Gear drive assembly 50 includes a first gear element 72selectively coupled to liner plate 32 a, a second gear element 74, asingle rod-end double-acting pneumatic cylinder (cylinder) 76 coupled tosecond gear element 74 via a piston rod 78, and a gear track 80.Cylinder 76 includes an aperture 82 for accepting a pneumatic fitting.In one embodiment, cylinder 76 comprises a hydraulic cylinder. In oneembodiment, cylinder 76 comprises a double rod-end dual-acting cylinder.In one embodiment, piston rod 78 is threadably coupled to second gearelement 74.

In the embodiment of FIG. 2, first gear element 72 and second gearelement 74 are illustrated and hereinafter referred to as a gear plate72 and second gear element 74, respectively. However, while illustratedas a gear plate and a cylindrical gear head, first gear element 72 andsecond gear element 74 can be of any suitable shape and dimension.

Gear plate 72 includes a plurality of angled channels on a first majorsurface 84 and is configured to slide in gear track 80. Gear track 80slidably inserts into a gear slot (not shown) extending into crossmember 36 a from inner wall 40 a. Cylindrical gear head 74 includes aplurality of angled channels on a surface 86 adjacent to first majorsurface 84 of female gear plate 72, wherein the angled channels aretangential to a radius of cylindrical gear head 74 and configured toslidably mate and interlock with the angled channels of gear plate 72.Liner plate 32 a includes guide posts 88 a, 88 b, 88 c, and 88 dextending from a rear surface 90. Each of the guide posts is configuredto slidably insert into a corresponding guide hole (not shown) extendinginto cross member 36 a from inner wall 40 a. The gear slot and guideholes are discussed in greater detail below.

When cylinder 76 extends piston rod 78, cylindrical gear head 74 movesin a direction indicated by arrow 92 and, due to the interlocking angledchannels, causes gear plate 72 and, thus, liner plate 32 a to movetoward the interior of mold 46 as indicated by arrow 94. It should benoted that, as illustrated, FIG. 2 depicts piston rod 78 and cylindricalgear head 74 in an extended position. When cylinder 76 retracts pistonrod 78, cylindrical gear head 74 moves in a direction indicated by arrow96 causing gear plate 72 and liner plate 32 to move away from theinterior of the mold as indicated by arrow 98. As liner plate 32 amoves, either toward or away from the center of the mold, gear plate 72slides in guide track 80 and guide posts 88 a through 88 d slide withintheir corresponding guide holes.

In one embodiment, a removable liner face 100 is selectively coupled tofront surface 44 a via fasteners 102 a, 102 b, 102 c, and 102 dextending through liner plate 32 a. Removable liner face 100 isconfigured to provide a desired shape and/or provide a desired imprintedpattern, including text, on a block made in mold 46. In this regard,removable liner face 100 comprises a negative of the desired shape orpattern. In one embodiment, removable liner face 100 comprises apolyurethane material. In one embodiment, removable liner face 100comprises a rubber material. In one embodiment, removable liner platecomprises a metal or metal alloy, such as steel or aluminum. In oneembodiment, liner plate 32 further includes a heater mounted in a recess104 on rear surface 90, wherein the heater aids in curing concretewithin mold 46 to reduce the occurrence of concrete sticking to frontsurface 44 a and removable liner face 100.

FIG. 3A is a top view 120 of gear drive assembly 50 and liner plate 32a, as indicated by directional arrow 106 in FIG. 2. In the illustration,side members 34 a and 34 b, and cross member 36 a are indicated dashedlines. Guide posts 88 c and 88 d are slidably inserted into guide holes122 c and 122 d, respectively, which extend into cross member 36 a frominterior surface 40 a. Guide holes 122 a and 122 b, correspondingrespectively to guide posts 88 a and 88 b, are not shown but are locatedbelow and in-line with guide holes 122 c and 122 d. In one embodiment,guide hole bushings 124 c and 124 d are inserted into guide holes 122 cand 122 d, respectively, and slidably receive guide posts 88 c and 88 d.Guide hole bushings 124 a and 124 b are not shown, but are located belowand in-line with guide hole bushings 124 c and 124 d. Gear track 80 isshown as being slidably inserted in a gear slot 126 extending throughcross member 36 a with gear plate 72 sliding in gear track 80. Gearplate 72 is indicated as being coupled to liner plate 32 a by aplurality of fasteners 128 extending through liner plate 32 a from frontsurface 44 a.

A cylindrical gear shaft is indicated by dashed lines 134 as extendingthrough side member 34 a and into cross member 36 a and intersecting, atleast partially with gear slot 126. Cylindrical gear head 74, cylinder76, and piston rod 78 are slidably inserted into gear shaft 134 withcylindrical gear head 74 being positioned over gear plate 72. The angledchannels of cylindrical gear head 74 are shown as dashed lines 130 andare interlocking with the angled channels of gear plate 72 as indicatedat 132.

FIG. 3B is a side view 140 of gear drive assembly 50 and liner plate 32a, as indicated by directional arrow 108 in FIG. 2. Liner plate 32 a isindicated as being extended, at least partially, from cross member 36 a.Correspondingly, guide posts 88 a and 88 d are indicated as partiallyextending from guide hole bushings 124 a and 124 d, respectively. In oneembodiment, a pair of limit rings 142 a and 142 d are selectivelycoupled to guide posts 88 a and 88, respectively, to limit an extensiondistance that liner plate 32 a can be extended from cross member 36 atoward the interior of mold cavity 46.

Limit rings 142 b and 142 c corresponding respectively to guide posts 88b and 88 c are not shown, but are located behind and in-line with limitrings 142 a and 142 d. In the illustrated embodiment, the limit ringsare indicated as being substantially at an end of the guide posts, thusallowing a substantially maximum extension distance from cross member 36a. However, the limit rings can be placed at other locations along theguide posts to thereby adjust the allowable extension distance.

FIG. 4A and FIG. 4B are top views 150 and 160, respectively, of moldassembly 30. FIG. 4A illustrates liner plates 32 a, 32 b, 32 c, and 32 din a refracted position. Liner faces 152, 154, and 154 correspondrespectively to liner plates 32 b, 32 c, and 32 d. FIG. 4B illustratesliner plates 32 a, 32 b, 32 c, and 32 d, along with their correspondingliner faces 100, 152, 154, and 156 in an extended position.

FIG. 5A is a top view 170 of gear plate 72. Gear plate 72 includes aplurality of angled channels 172 running across a top surface 174 ofgear plate 72. Angled channels 172 form a corresponding plurality oflinear “teeth” 176 having as a surface the top surface 174. Each angledchannel 172 and each tooth 176 has a respective width 178 and 180. Theangled channels run at an angle (Θ) 182 from 0°, indicated at 186,across gear plate 72.

FIG. 5B is an end view (“A”) 185 of gear plate 72, as indicated bydirectional arrow 184 in FIG. 5A, further illustrating the plurality ofangled channels 172 and linear teeth 176. Each angled channel 172 has adepth 192.

FIG. 5C illustrates a view 200 of a flat surface 202 of cylindrical gearhead 76. Cylindrical gear head 76 includes a plurality of angledchannels 204 running across surface 202. Angled channels 204 form acorresponding plurality of linear teeth 206. The angled channels 204 andlinear teeth 206 have widths 180 and 178, respectively, such that thewidth of linear teeth 206 substantially matches the width of angledchannels 172 and the width of angled channels 204 substantially matchthe width of linear teeth 176. Angled channels 204 and teeth 206 run atangle (Θ) 182 from 0°, indicated at 186, across surface 202.

FIG. 5D is an end view 210 of cylindrical gear head 76, as indicated bydirectional arrow 208 in FIG. 5C, further illustrating the plurality ofangled channels 204 and linear teeth 206. Surface 202 is a flat surfacetangential to a radius of cylindrical gear head 76. Each angled channelhas a depth 192 from flat surface 202.

When cylindrical gear head 76 is “turned over” and placed across surface174 of gear plate 72, linear teeth 206 of gear head 76 mate andinterlock with angled channels 172 of gear plate 72, and linear teeth176 of gear plate 72 mate and interlock with angled channels 204 of gearhead 76 (See also FIG. 2). When gear head 76 is forced in direction 92,linear teeth 206 of gear head 76 push against linear teeth 176 of gearplate 72 and force gear plate 72 to move in direction 94. Conversely,when gear head 76 is forced in direction 96, linear teeth 206 of gearhead 76 push against linear teeth 176 of gear plate 72 and force gearplate 72 to move in direction 98.

In order for cylindrical gear head 76 to force gear plate 72 indirections 94 and 98, angle (Θ) 182 must be greater than 0° and lessthan 90°. However, it is preferable that Θ 182 be at least greater than45°. When Θ 182 is 45° or less, it takes more force for cylindrical gearhead 74 moving in direction 92 to push gear plate 72 in direction 94than it does for gear plate 72 being forced in direction 98 to pushcylindrical gear head 74 in direction 96, such as when concrete in mold46 is being compressed. The more Θ 182 is increased above 45°, thegreater the force that is required in direction 98 on gear plate 72 tomove cylindrical gear head 74 in direction 96. In fact, at 90° gearplate 72 would be unable to move cylindrical gear head 74 in eitherdirection 92 or 96, regardless of how much force was applied to gearplate 72 in direction 98. In effect, angle (Θ) acts as a multiplier to aforce provided to cylindrical gear head 74 by cylinder 76 via piston rod78. When Θ 182 is greater than 45°, an amount of force required to beapplied to gear plate 72 in direction 98 in order to move cylindricalgear head 74 in direction 96 is greater than an amount of force requiredto be applied to cylindrical gear head 74 in direction 92 via piston rod78 in order to “hold” gear plate 72 in position (i.e., when concrete isbeing compressed in mold 46).

However, the more Θ 182 is increased above 45°, the less distance gearplate 72, and thus corresponding liner plate 32 a, will move indirection 94 when cylindrical gear head 74 is forced in direction 92. Apreferred operational angle for Θ 182 is approximately 70°. This anglerepresents roughly a balance, or compromise, between the length oftravel of gear plate 72 and an increase in the level of force requiredto be applied in direction 98 on gear plate 72 to force gear head 74 indirection 96. Gear plate 72 and cylindrical gear head 74 and theircorresponding angled channels 176 and 206 reduce the required psi ratingof cylinder 76 necessary to maintain the position of liner plate 32 awhen concrete is being compressed in mold cavity 46 and also reduces thewear experienced by cylinder 76. Additionally, from the abovediscussion, it is evident that one method for controlling the traveldistance of liner plate 32 a is to control the angle (Θ) 182 of theangled channels 176 and 206 respectively of gear plate 72 andcylindrical gear head 74.

FIG. 6A is a top view 220 of gear track 80. Gear track 80 has a topsurface 220, a first end surface 224, and a second end surface 226. Arectangular gear channel, indicated by dashed lines 228, having a firstopening 230 and a second opening 232 extends through gear track 80. Anarcuate channel 234, having a radius required to accommodate cylindricalgear head 76 extends across top surface 220 and forms a gear window 236extending through top surface 222 into gear channel 228. Gear track 80has a width 238 incrementally less than a width of gear opening 126 inside member 36 a (see also FIG. 3A).

FIG. 6B is an end view 250 of gear track 80, as indicated by directionarrow 240 in FIG. 6A, further illustrating gear channel 228 and arcuatechannel 234. Gear track 80 has a depth 252 incrementally less thanheight of gear opening 126 in side member 36 a (see FIG. 3A). FIG. 6B isa side view 260 of gear track 80 as indicated by directional arrow 242in FIG. 6A.

FIG. 7 is a top view 270 illustrating the relationship between geartrack 80 and gear plate 72. Gear plate 72 has a width 272 incrementallyless than a width 274 of gear track 80, such that gear plate 72 can beslidably inserted into gear channel 228 via first opening 230. When gearplate 72 is inserted within gear track 80, angled channels 172 andlinear teeth 176 are exposed via gear window 236.

FIG. 8A is a top view 280 illustrating the relationship between gearplate 72, cylindrical gear head 74, and gear track 80. Gear plate 72 isindicated as being slidably inserted within guide track 80. Cylindricalgear head 74 is indicated as being positioned within arcuate channel234, with the angled channels and linear teeth of cylindrical gear head74 being slidably mated and interlocked with the angled channels 172 andlinear teeth 176 of gear plate 72. When cylindrical gear head 74 ismoved in direction 92 by extending piston rod 78, gear plate 72 extendsoutward from gear track 80 in direction 94 (See also FIG. 9B below).When cylindrical gear head 74 is moved in direction 96 by retractingpiston rod 78, gear plate 72 retracts into gear track 80 in direction 98(See also FIG. 9A below).

FIG. 8B is a side view 290 of gear plate 72, cylindrical gear head 74,and guide track 80 as indicated by directional arrow 282 in FIG. 8A.Cylindrical gear head 74 is positioned such that surface 202 is locatedwithin arcuate channel 234. Angled channels 204 and teeth 206 ofcylindrical gear head 74 extend through gear window 236 and interlockwith angled channels 172 and linear teeth 176 of gear plate 72 locatedwithin gear channel 228. FIG. 8C is an end view 300 as indicated bydirectional arrow 284 in FIG. 8A, and further illustrates therelationship between gear plate 72, cylindrical gear head 74, and guidetrack 80.

FIG. 9A is top view 310 illustrating gear plate 72 being in a fullyretracted position within gear track 80, with liner plate 32 a beingretracted against cross member 36 a. For purposes of clarity,cylindrical gear head 74 is not shown. Angled channels 172 and linearteeth 176 are visible through gear window 236. Liner plate 32 a isindicated as being coupled to gear plate 72 with a plurality offasteners 128 extending through liner plate 32 a into gear plate 72. Inone embodiment, fasteners 128 threadably couple liner plate 32 a to gearplate 72.

FIG. 9B is a top view 320 illustrating gear plate 72 being extended, atleast partially from gear track 80, with liner plate 32 a beingseparated from cross member 36 a. Again, cylindrical gear head 74 is notshown and angled channels 172 and linear teeth 176 are visible throughgear window 236.

FIG. 10A is a diagram 330 illustrating one exemplary embodiment of agear drive assembly 332 according to the present invention. Gear driveassembly 332 includes cylindrical gear head 74, cylinder 76, piston rod78, and a cylindrical sleeve 334. Cylindrical gear head 74 and pistonrod 78 are configured to slidably insert into cylindrical sleeve 334.Cylinder 76 is threadably coupled to cylindrical sleeve 334 with anO-ring 336 making a seal. A window 338 along an axis of cylindricalsleeve 334 partially exposes angled channels 204 and linear teeth 206. Afitting 342, such as a pneumatic or hydraulic fitting, is indicated asbeing threadably coupled to aperture 82. Cylinder 76 further includes anaperture 344, which is accessible through cross member 36 a.

Gear drive assembly 332 is configured to slidably insert intocylindrical gear shaft 134 (indicated by dashed lines) so that window338 intersects with gear slot 126 so that angled channels 204 and linearteeth 206 are exposed within gear slot 126. Gear track 80 and gear plate72 (not shown) are first slidably inserted into gear slot 126, such thatwhen gear drive assembly 332 is slidably inserted into cylindrical gearshaft 134 the angled channels 204 and linear teeth 206 of cylindricalgear head 74 slidably mate and interlock with the angled channels 172and linear teeth 176 of gear plate 72.

In one embodiment, a key 340 is coupled to cylindrical gear head 74 andrides in a key slot 342 in cylindrical sleeve 334. Key 340 preventscylindrical gear head 74 from rotating within cylindrical sleeve 334.Key 340 and key slot 342 together also control the maximum extension andretraction of cylindrical gear head 74 within cylindrical sleeve 334.Thus, in one embodiment, key 340 can be adjusted to control theextension distance of liner plate 32 a toward the interior of moldcavity 46. FIG. 10A is a top view 350 of cylindrical shaft 334 asillustrated in FIG. 10B, and further illustrates key 340 and key slot342.

FIG. 11A is a top view illustrating one exemplary embodiment of a moldassembly 360 according to the present invention for forming two concreteblocks. Mold assembly 360 includes a mold frame 361 having side members34 a and 34 b and cross members 36 a through 36 c coupled to one anotherso as to form a pair of mold boxes 42 a and 42 b. Mold box 42 a includesmoveable liner plates 32 a through 32 d and corresponding removableliner faces 33 a through 33 d configured to form a mold cavity 46 a.Mold box 42 b includes moveable liner plates 32 e through 32 h andcorresponding removable liner faces 33 e through 33 h configured to forma mold cavity 46 b.

Each moveable liner plate has an associated gear drive assembly locatedinternally to an adjacent mold frame member as indicated by 50 a through50 h. Each moveable liner plate is illustrated in an extended positionwith a corresponding gear plate indicated by 72 a through 72 h. Asdescribed below, moveable liner plates 32 c and 32 e share gear driveassembly 50 c/e, with gear plate 72 e having its corresponding pluralityof angled channels facing upward and gear plate 72 c having itscorresponding plurality of angled channels facing downward.

FIG. 11B is diagram illustrating a gear drive assembly according to thepresent invention, such as gear drive assembly 50 c/e. FIG. 11Billustrates a view of gear drive assembly 50 c/e as viewed from sectionA-A through cross-member 36 c of FIG. 11A. Gear drive assembly 50 c/eincludes a single cylindrical gear head 76 c/e having angled channels204 c and 204 e on opposing surfaces. Cylindrical gear head 76 c/e fitsinto arcuate channels 234 c and 234 e of gear tracks 80 c and 80 d, suchthat angled channels 204 c and 204 e slidably interlock with angledchannels 172 c and 172 e of gear plates 72 c and 72 e respectively.

Angled channels 172 c and 204 c, and 172 e and 204 e oppose one anotherand are configured such that when cylindrical gear head 76 c/e isextended (e.g. out from FIG. 11B) gear plate 72 c moves in a direction372 toward the interior of mold cavity 46 a and gear plate 72 e moves ina direction 374 toward the interior of mold cavity 46 b. Similarly, whencylindrical gear head 76 c/e is retracted (e.g. into FIG. 11B) gearplate 72 c moves in a direction 376 away from the interior of moldcavity 46 a and gear plate 72 e moves in a direction 378 away from theinterior of mold cavity 378. Again, cylindrical gear head 76 c/e andgear plates 72 c and 72 c could be of any suitable shape.

FIG. 12 is a perspective view illustrating a portion of one exemplaryembodiment of a mold assembly 430 according to the present invention.Mold assembly includes moveable liner plates 432 a through 4321 forsimultaneously molding multiple concrete blocks. Mold assembly 430includes a drive system assembly 431 having a side members 434 a and 434b, and cross members 436 a and 436 b. For illustrative purposes, sidemember 434 a is indicated by dashed lines. Mold assembly 430 furtherincludes division plates 437 a through 437 g.

Together, moveable liner plates 432 a through 4321 and division plates437 a through 437 g form mold cavities 446 a through 446 f, with eachmold cavity configured to form a concrete block. Thus, in theillustrated embodiment, mold assembly 430 is configured tosimultaneously form six blocks. However, it should be apparent from theillustration that mold assembly 430 can be easily modified forsimultaneously forming quantities of concrete blocks other than six.

In the illustrated embodiment, side members 434 a and 434 b each have acorresponding gear drive assembly for moving moveable liner plates 432 athrough 432 f and 432 g through 4321, respectively. For illustrativepurposes, only gear drive assembly 450 associated with side member 434 aand corresponding moveable liner plates 432 a through 432 g is shown.Gear drive assembly 450 includes first gear elements 472 a through 472 fselectively coupled to corresponding moveable liner plates 432 a through432 f, respectively, and a second gear element 474. In the illustratedembodiment, first gear elements 472 a through 472 f and second gearelement 474 are shown as being cylindrical in shape. However, anysuitable shape can be employed.

Second gear element 474 is selectively coupled to a cylinder-piston (notshown) via a piston rod 478. In one embodiment, which is described ingreater detail below (see FIG. 12), second gear element 474 is integralwith the cylinder-piston so as to form a single component.

In the illustrated embodiment, each first gear element 472 a through 472b further includes a plurality of substantially parallel angled channels484 that slidably mesh and interlock with a plurality of substantiallyparallel angled channels 486 on second gear element 474. When secondgear element 474 is moved in a direction indicated by arrow 492, each ofthe moveable liner plates 432 a through 432 f moves in a directionindicated by arrow 494. Similarly, when second gear element 474 is movein a direction indicated by arrow 496, each of the moveable liner plates432 a through 432 f moves in a direction indicated by arrow 498.

In the illustrated embodiment, the angled channels 484 on each of thefirst gear elements 432 a through 432 f and the angled channels 486 areat a same angle. Thus, when second gear element 474 moves in direction492 and 496, each moveable liner plate 432 a through 432 f moves a samedistance in direction 494 and 498, respectively. In one embodiment,second gear element 474 includes a plurality of groups of substantiallyparallel angled channels with each group corresponding to a differentone of the first gear elements 472 a through 472 f. In one embodiment,the angled channels of each group and its corresponding first gearelement have a different angle such that each moveable liner plate 432 athrough 432 f move a different distance in directions 494 and 498 inresponse to second gear element 474 being moved in direction 492 and496, respectively.

FIG. 13 is a perspective view illustrating a gear drive assembly 500according to the present invention, and a corresponding moveable linerplate 502 and removable liner face 504. For illustrative purposes, aframe assembly including side members and cross members is not shown.Gear drive assembly 500 includes double rod-end, dual-acting pneumaticcylinder-piston 506 having a cylinder body 507, and a hollow piston rod508 with a first rod-end 510 and a second rod-end 512. Gear driveassembly 500 further includes a pair of first gear elements 514 a and514 b selectively coupled to moveable liner plate 502, with each firstgear element 514 a and 514 b having a plurality of substantiallyparallel angled channels 516 a and 516 b.

In the illustrated embodiment, cylinder body 507 of cylinder-piston 506includes a plurality of substantially parallel angled channels 518configured to mesh and slidably interlock with angled channels 516 a and516 b. In one embodiment, cylinder body 507 is configured to slidablyinsert into and couple to a cylinder sleeve having angled channels 518.

In one embodiment, cylinder-piston 506 and piston rod 508 are locatedwithin a drive shaft of a frame member, such as drive shaft 134 ofcross-member 36 a, with rod-end 510 coupled to and extending through aframe member, such as side member 34 b, and second rod-end 512 coupledto and extending through a frame member, such a side member 34 a. Firstrod-end 510 and second rod-end 512 are configured to receive and providecompressed air to drive dual-acting cylinder-piston 506. With piston rod508 being fixed to side members 34 a and 34 b via first and secondrod-ends 512 and 510, cylinder-piston 506 travels along the axis ofpiston rod 508 in the directions as indicated by arrows 520 and 522 inresponse to compressed air received via first and second rod-ends 510and 512.

When compressed air is received via second rod-end 512 and expelled viafirst rod-end 510, cylinder-piston 506 moves within a drive shaft, suchas drive shaft 134, in direction 522 and causes first gear elements 514a and 516 b and corresponding liner plate 502 and liner face 504 to movein a direction indicated by arrow 524. Conversely, when compressed airis received via first rod-end 510 and expelled via second rod-end 512,cylinder-piston 506 moves within a gear shaft, such as gear shaft 134,in direction 520 and causes first gear elements 514 a and 516 b andcorresponding liner plate 502 and liner face 504 to move in a directionindicated by arrow 526.

In the illustrated embodiment, cylinder-piston 506 and first gearelements 514 a and 514 b are shown as being substantially cylindrical inshape. However, any suitable shape can be employed. Furthermore, in theillustrated embodiment, cylinder-piston 506 is a double rod-enddual-acting cylinder. In one embodiment, cylinder piston 506 is a singlerod-end dual acting cylinder having only a single rod-end 510 coupled toa frame member, such as side member 34 b. In such an embodiment,compressed air is provided to cylinder-piston via single rod-end 510 anda flexible pneumatic connection made to cylinder-piston 506 through sidemember 34 a via gear shaft 134. Additionally, cylinder-piston 506comprises a hydraulic cylinder.

FIG. 14 is a top view of a portion of mold assembly 430 (as illustratedby FIG. 12) having a drive assembly 550 according to one embodiment ofthe present invention.

Drive assembly 550 includes first drive elements 572 a to 572 f that areselectively coupled to corresponding liner plates 432 a to 432 f viaopenings, such as opening 433, in side member 434 a. Each of the firstdrive elements 572 a to 572 if further coupled to a master bar 573.Drive assembly 550 further includes a double-rod-end hydraulic pistonassembly 606 having a dual-acting cylinder 607 and a hollow piston rod608 having a first rod-end 610 and a second rod-end 612. First andsecond rod-ends 610, 612 are stationary and are coupled to and extendthrough a removable housing 560 that is coupled to side member 434 a andencloses drive assembly 550. First and second rod ends 610, 612 are eachcoupled to hydraulic fittings 620 that are configured to connect vialines 622 a and 622 b to an external hydraulic system 624 and totransfer hydraulic fluid to and from dual-acting cylinder 607 via hollowpiston rod 608.

In one embodiment, as illustrated, first drive elements 572 b and 572 einclude a plurality of substantially parallel angled channels 616 thatslideably interlock with a plurality of substantially parallel angledchannels 618 that form a second drive element. In one embodiment, asillustrated above by FIG. 12, angled channels 618 are formed ondual-acting cylinder 607 of hydraulic piston assembly 606, such thatdual-acting cylinder 607 forms the second drive element. In otherembodiments, as will be described by FIGS. 15A-15C below, the seconddrive element is separate from and operatively coupled to dual-actingcylinder 607.

When hydraulic fluid is transmitted into dual-acting cylinder 607 fromsecond rod-end 612 via fitting 620 and hollow piston rod 608, hydraulicfluid is expelled from first rod-end 610, causing dual-acting cylinder607 and angled channels 618 to move along piston rod 608 toward secondrod-end 612. As dual-acting cylinder 607 moves toward second rod-end612, angled channels 618 interact with angled channels 616 and drivefirst drive elements 572 b and 572 e, and thus corresponding linerplates 432 b and 432 e, toward the interior of mold cavities 446 b and446 e, respectively. Furthermore, since each of the first drive elements572 a through 572 f is coupled to master bar 573, driving first gearelements 572 b and 572 e toward the interiors of mold cavities 446 b and446 e also moves first drive elements 572 a, 572 c, 572 d, and 572 f andcorresponding liner plates 432 a, 432 c, 432 d, and 432 e toward theinteriors of mold cavities 446 a, 446 c, 446 d, and 446 f, respectively.Conversely, transmitting hydraulic fluid into dual-acting cylinder 607from first rod-end 610 via fitting 620 and hollow-piston rod 608 causesdual-acting cylinder 607 to move toward first rod-end 610, and causesliner plates 432 to move away from the interiors of corresponding moldcavities 446.

In one embodiment, drive assembly 550 further includes support shafts626, such as support shafts 626 a and 626 b, which are coupled betweenremovable housing 560 and side member 434 a and extend through masterbar 573. As dual-acting cylinder 607 is moved by transmitting/expellinghydraulic fluid from first and second rod-ends 610, 612, master bar 573moves back and forth along support shafts 626. Because they are coupledto static elements of mold assembly 430, support shafts 626 a and 626 bprovide support and rigidity to liner plates 432, drive elements 572,and master bar 573 as they move toward and away from mold cavities 446.

In one embodiment, drive assembly 550 further includes a pneumaticfitting 628 configured to connect via line 630 to and externalcompressed air system 632 and provide compressed air to housing 560. Byreceiving compressed air via pneumatic fitting 628 to removable housing560, the internal air pressure of housing 560 is positive relative tothe outside air pressure, such that air is continuously “forced” out ofhousing 560 through any non-sealed openings, such as openings 433through which first drive elements 572 extend through side member 434 a.By maintaining a positive air pressure and forcing air out through suchnon-sealed opening, the occurrence of dust and debris and other unwantedcontaminants from entering housing 560 and fouling drive assembly 550 isreduced.

First and second rod ends 610, 612 are each coupled to hydraulicfittings 620 that are configured to connect via lines 622 a and 622 b toan external hydraulic system 624 and to transfer hydraulic fluid to andfrom dual-acting cylinder 607 via hollow piston rod 608.

FIG. 15A is a top view illustrating a portion of one embodiment of driveassembly 550 according to the present invention. Drive assembly 550includes double-rod-end hydraulic piston assembly 606 comprisingdual-acting cylinder 607 and a hollow piston rod 608 with first andsecond rod-ends 610 and 612 being and coupled to and extending throughremovable housing 560.

As illustrated, dual-acting cylinder 607 is slideably-fitted inside amachined opening 641 within a second gear element 640, with hollowpiston rod 608 extending through removable end caps 642. In oneembodiment, end caps 646 are threadably inserted into machined opening641 such that end caps 646 butt against and secure dual-acting cylinder607 so that dual-acting cylinder 607 is held stationary with respect tosecond drive element 640. Second drive element 640 includes theplurality of substantially parallel angled channels 618, in lieu ofangled channels being an integral part of dual-acting cylinder 607. Withreference to FIG. 14, angled channels 618 of second gear element 640 areconfigured to slideably interlock with angled channels 616 of first gearelements 572 b and 572 e.

Second gear element 640 further includes a guide rail 644 that isslideably coupled to linear bearing blocks 646 that are mounted tohousing 560. As described above with respect to FIG. 14, transmittingand expelling hydraulic fluid to and from dual-acting cylinder 607 viafirst and second rod-ends 610, 612 causes dual-acting cylinder 607 tomove along hollow piston-rod 608. Since dual-acting cylinder 607 is“locked” in place within machined shaft 641 of second gear element 640by end caps 642, second gear element 640 moves along hollow piston-rod608 together with dual-acting cylinder 607. As second drive element 640moves along hollow piston-rod 608, linear bearing blocks 646 guide andsecure guide rail 644, thereby guiding and securing second drive element640 and reducing undesirable motion in second drive element 640 that isperpendicular to hollow piston rod 608.

FIG. 15B is a lateral cross-sectional view A-A of the portion of driveassembly 550 illustrated by FIG. 15A. Guide rail 644 is slideably fittedinto a linear bearing track 650 and rides on bearings 652 as seconddrive element 640 is moved along piston rod 608 by dual-acting cylinder607. In one embodiment, linear bearing block 646 b is coupled to housing560 via bolts 648.

FIG. 15C is a longitudinal cross-sectional view B-B of the portion ofdrive assembly 550 of FIG. 15A, and illustrates dual-acting cylinder 607as being secured within shaft 641 of drive element 640 by end caps 642 aand 642 b. In one embodiment, end caps 642 a and 642 b are threadablyinserted into the ends of second drive element 640 so as to butt againsteach end of dual-acting cylinder 607. Hollow piston rod 608 extendsthrough end caps 642 a and 642 b and has first and second rod ends 610and 612 coupled to and extending through housing 560. A divider 654 iscoupled to piston rod 608 and divides dual-acting cylinder 607 into afirst chamber 656 and a second chamber 658. A first port 660 and asecond port 662 allow hydraulic fluid to be pumped into and expelledfrom first chamber 656 and second chamber 658 via first and second rodends 610 and 612 and associated hydraulic fittings 620, respectively.

When hydraulic fluid is pumped into first chamber 656 via first rod-end610 and first port 660, dual-acting cylinder 607 moves along hollowpiston rod 608 toward first rod-end 610 and hydraulic fluid is expelledfrom second chamber 658 via second port 662 and second rod-end 612.Since dual-acting cylinder 607 is secured within shaft 641 by end caps642 a and 642 b, second drive element 640 and, thus, angled channels 618move toward first rod-end 610. Similarly, when hydraulic fluid is pumpedinto second chamber 658 via second rod-end 612 and second port 662,dual-acting cylinder 607 moves along hollow piston rod 608 toward secondrod-end 612 and hydraulic fluid is expelled from first chamber 656 viafirst port 660 and first rod-end 610.

FIG. 16 is a side view of a portion of drive assembly 550 as shown byFIG. 14 and illustrates a typical liner plate, such as liner plate 432a, and corresponding removable liner face 400. Liner plate 432 a iscoupled to second drive element 572 a via a bolted connection 670 and,in-turn, drive element 572 a is coupled to master bar 573 via a boltedconnection 672. A lower portion of liner face 400 is coupled to linerplate 432 a via a bolted connection 674. In one embodiment, asillustrated, liner plate 432 a includes a raised “rib” 676 that runs thelength of and along an upper edge of liner plate 432 a. A channel 678 inliner face 400 overlaps and interlocks with raised rib 676 to form a“boltless” connection between liner plate 432 a and an upper portion ofliner face 400. Such an interlocking connection securely couples theupper portion of liner face 400 to liner plate 432 in an area of linerface 400 that would otherwise be too narrow to allow use of a boltedconnection between liner face 400 and liner plate 432 a without the boltbeing visible on the surface of liner face 400 that faces mold cavity446 a.

In one embodiment, liner plate 432 includes a heater 680 configured tomaintain the temperature of corresponding liner face 400 at a desiredtemperature to prevent concrete in corresponding mold cavity 446sticking to a surface of liner face 400 during a concrete curingprocess. In one embodiment, heater 680 comprises an electric heater.

FIG. 17 is a block diagram illustrating one embodiment of a moldassembly according to the present invention, such as mold assembly 430of FIG. 14, further including a controller 700 configured to coordinatethe movement of moveable liner plates, such as liner plates 432, withoperations of concrete block machine 702 by controlling the operation ofthe drive assembly, such as drive assembly 550. In one embodiment, asillustrated, controller 700 comprises a programmable logic controller(PLC).

As described above with respect to FIG. 1, mold assembly 430 isselectively coupled, generally via a plurality of bolted connections, toconcrete block machine 702. In operation, concrete block machine 702first places pallet 56 below mold box assembly 430. A concrete feedbox704 then fills mold cavities, such as mold cavities 446, of assembly 430with concrete. Head shoe assembly 52 is then lowered onto mold assembly430 and hydraulically or mechanically compresses the concrete in moldcavities 446 and, together with a vibrating table on which pallet 56 ispositioned, simultaneously vibrates mold assembly 430. After thecompression and vibration is complete, head shoe assembly 52 and pallet56 are lowered relative to mold cavities 446 so that the formed concreteblocks are expelled from mold cavities 446 onto pallet 56. Head shoeassembly 52 is then raised and a new pallet 56 is moved into positionbelow mold cavities 446. The above process is continuously repeated,with each such repetition commonly referred to as a cycle. With specificreference to mold assembly 430, each such cycle produces six concreteblocks.

PLC 700 is configured to coordinate the extension and retraction ofliner plates 432 into and out of mold cavities 446 with the operationsof concrete block machine 702 as described above. At the start of acycle, liner plates 432 are fully retracted from mold cavities 446. Inone embodiment, with reference to FIG. 14, drive assembly 550 includes apair of sensors, such as proximity switches 706 a and 706 b to monitorthe position of master bar 573 and, thus, the positions of correspondingmoveable liner plates 432 coupled to master bar 573. As illustrated inFIG. 14, proximity switches 706 a and 706 b are respectively configuredto detect when liner plates 432 are in an extended position and aretracted position with respect to mold cavities 446.

In one embodiment, after pallet 56 has been positioned beneath moldassembly 430, PLC 700 receives a signal 708 from concrete block machine702 indicating that concrete feedbox 704 is ready to deliver concrete tomold cavities 446. PLC 700 checks the position of moveable liners 432based on signals 710 a and 710 b received respectively from proximityswitches 706 a and 706 b. With liner plates 432 in a retracted position,PLC 700 provides a liner extension signal 712 to hydraulic system 624.

In response to liner extension signal 712, hydraulic system 624 beginspumping hydraulic fluid via path 622 b to second rod-end 612 of pistonassembly 606 and begins receiving hydraulic fluid from first rod-end 610via path 622 a, thereby causing dual-acting cylinder 607 to begin movingliner plates 432 toward the interiors of mold cavities 446. Whenproximity switch 706 a detects master bar 573, proximity switch 706 aprovides signal 710 a to PLC 700 indicating that liner plates 432 havereached the desired extended position. In response to signal 710 a, PLC700 instructs hydraulic system 624 via signal 712 to stop pumpinghydraulic fluid to piston assembly 606 and provides a signal 714 toconcrete block machine 702 indicating that liner plates 432 areextended.

In response to signal 714, concrete feedbox 704 fills mold cavities 446with concrete and head shoe assembly 52 is lowered onto mold assembly430. After the compression and vibrating of the concrete is complete,concrete block machine 702 provides a signal 716 indicating that theformed concrete blocks are ready to be expelled from mold cavities 446.In response to signal 716, PLC 700 provides a liner retraction signal718 to hydraulic system 624.

In response to liner retraction signal 718, hydraulic system 624 beginspumping hydraulic fluid via path 622 a to first rod-end 610 via path 622and begins receiving hydraulic fluid via path 622 b from second rod-end612, thereby causing dual-acting cylinder 607 to begin moving linerplates 432 away from the interiors of mold cavities 446. When proximityswitch 706 b detects master bar 573, proximity switch 706 b providessignal 710 b to PLC 700 indicating that liner plates 432 have reached adesired retracted position. In response to signal 710 b, PLC 700instructs hydraulic system 624 via signal 718 to stop pumping hydraulicfluid to piston assembly 606 and provides a signal 720 to concrete blockmachine 702 indicating that liner plates 432 are refracted.

In response to signal 720, head shoe assembly 52 and pallet 56 eject theformed concrete blocks from mold cavities 446. Concrete block machine702 then retracts head shoe assembly 52 and positions a new pallet 56below mold assembly 430. The above process is then repeated for the nextcycle.

In one embodiment, PLC 700 is further configured to control the supplyof compressed air to mold assembly 430. In one embodiment, PLC 700provides a status signal 722 to compressed air system 630 indicative ofwhen concrete block machine 702 and mold assembly 430 are in operationand forming concrete blocks. When in operation, compressed air system632 provides compressed air via line 630 and pneumatic fitting 628 tohousing 560 of mold assembly 420 to reduce the potential for dirt/dustand other debris from entering drive assembly 550. When not inoperation, compressed air system 632 does not provide compressed air tomold assembly 430.

Although the above description of controller 700 is in regard tocontrolling a drive assembly employing only a single piston assembly,such as piston assembly 606 of drive assembly 500, controller 700 can beadapted to control drive assemblies employing multiple piston assembliesand employing multiple pairs of proximity switches, such as proximityswitches 706 a and 706 b. In such instances, hydraulic system 624 wouldbe coupled to each piston assembly via a pair of hydraulic lines, suchas lines 622 a and 622 b. Additionally, PLC 700 would receive multipleposition signals and would respectively allow mold cavities to be filledwith concrete and formed blocks to be ejected only when each applicableproximity switch indicates that all moveable liner plates are at theirextended position and each applicable proximity switch indicates thatall moveable liner plates are at their retracted position.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat a variety of alternate and/or equivalent implementations may besubstituted for the specific embodiments shown and described withoutdeparting from the scope of the present invention. This application isintended to cover any adaptations or variations of the specificembodiments discussed herein. Therefore, it is intended that thisinvention be limited only by the claims and the equivalents thereof.

1. A mold assembly for molding concrete blocks comprising: at least onemold cavity having sides walls formed by a plurality of liner plates, atleast one of which is moveable between an extended position and aretracted position relative to an interior of the mold cavity, in whichdry cast concrete is compressed when the at least one moveable linerplate is in the extended position to form a dry cast concrete block; anactuator positioned external to the mold cavity and having an actuatoraxis; a first drive linkage in mechanical communication with themoveable liner plate and positioned off-axis from the actuator axis; anda second drive linkage operatively coupled to the first drive linkage,wherein the actuator is configured to provide a first force having afirst magnitude in a one direction along the actuator axis to the seconddrive element to push the first drive element in a first directiontoward the interior of the mold cavity and move the at least one movableliner plate to the extended position and to provide a second forcehaving the first magnitude in the opposite direction along the actuatoraxis to the second drive element to pull the first element opposite thefirst direction away from the interior of the mold, and wherein thefirst and second drive linkage are configured as a force multiplier suchthat the first magnitude of the first and second forces is less than amagnitude of a force which is required to be applied to the at least onemoveable liner plate in a direction opposite the first direction fromcompression of dry cast concrete in the mold cavity to push the at leastone moveable liner plate and the first drive element in the directionopposite the first direction.
 2. The mold assembly of claim 1, whereinan actual magnitude of the force applied by compression of dry castconcrete in the mold cavity is less than the required force.
 3. The moldassembly of claim 1, wherein the actuator comprises a linear actuator.4. The mold assembly of claim 3, wherein the actuator comprises apiston.
 5. The mold assembly of claim 1, wherein the actuator provides arotational force.